Two-Step System For Improved Initial And Final Characteristics Of A Biomaterial

Abstract

A two-step system for chemically bonded ceramic (CBC) materials, and especially a dental filling material or an implant material. The system includes an initial working part-system to provide for improved early-age properties and a second main system to provide for improved end-product properties including bioactivity. The systems interact chemically. The invention also relates to the powdered materials and the hydration liquid, respectively, as well as the formed ceramic material.

1 . A system for a chemically bonded material, comprising
 an aqueous hydration liquid;   a powdered material comprising a first binder phase (c), which powdered material has the capacity following saturation with the liquid reacting with said first binder phase to hydrate to a chemically bonded ceramic material;   a second, non-ceramic binder phase having a different initiation time for setting and/or a different setting rate than the initiation time for hydration and the hydration rate, respectively, of said first binder phase,   characterised in that the system further comprises a reactive glass; and   a second portion of aqueous hydration liquid (w GIC ), wherein
     w=w   c   +w   GIC    
   (w c /c)+(second binder phase)/(reactive glass)+W GIC / (reactive glass) 
   with 0.2<w c /c<0.45, 0<(second binder phase)/(reactive glass)<0.21 and 0.2<W GIC /(reactive glass)<0.45, and in that the system provides for an ionic interaction between the hydration reactions and setting reactions of the first binder phase (c) and the second binder phase, respectively.   
     
     
         2 . A system according to  claim 1 , characterised in that it is adapted to enable an initial pH to be kept <7, more preferably <4 and most preferably 1-3 to control properties related to different initiation time for setting and hardening of the part systems. 
     
     
         3 . A system according to  claim 1 , characterised in that the second binder phase comprises a polycarboxylic acid and/or a copolymer or a salt or an ester thereof providing a pH value in the system of <7, preferably <4 for the first 20 minutes after mixing, preferably, a pH in the interval 1-4 for the first 10 minutes, and most preferably for the first 5 minutes. 
     
     
         4 . A system according to  claim 1 , characterised in that a base is comprised in the system, so as to achieve a change of the pH to a pH>7, more preferably a pH>10, after an initial period of time after mixing of the system of a few minutes up to approximately 5 minutes at pH<7. 
     
     
         5 . A system according to  claim 1 , characterised in that an additional acid is comprised in the system, so as to keep the pH<7 during a prolonged time of up to 30 minutes, preferably up to 20 minutes. 
     
     
         6 . A system according to  claim 4 , characterised in that the system comprises a porous material, preferably a nano/meso-pore structure or a zeolite type structure, that is able to release said base. 
     
     
         7 . A system according to  claim 1 , characterised in that particles of said first binder phase are coated with a dissolution-reducing layer, preferably comprising a glyconate. 
     
     
         8 . A system according to  claim 1 , characterised in that it comprises inert filler particles composed of pre-hydrated chemically bonded ceramics, preferably of the same composition as said first binder phase. 
     
     
         9 . A system according to  claim 1 , characterised in that it comprises semihydrate of CaSO 4  and/or a combination of phosphoric acid and zinc oxide-forming Zn-phosphate. 
     
     
         10 . A system according to  claim 1 , characterised in that the system yields an initial strength above 5 MPa measured by diametral tensile strength after 15 minutes. 
     
     
         11 . A powdered material for dental or orthopaedic applications for use in the system of  claim 1 , comprising a first binder phase essentially consisting of a cement system, which powdered material has the capacity following saturation with a hydration liquid reacting with said first binder phase to hydrate to a chemically bonded ceramic material, and an additive of a second, non-ceramic binder phase having a different initiation time for setting and/or a different setting rate than the initiation time for hydration and the hydration rate, respectively, of said first binder phase, characterised in that the powdered material comprises a reactive glass and that the second binder phase comprises a polycarboxylic acid or a copolymer or a salt or an ester thereof having a molecular weight of 100-250,000, preferably 1000-100,000, in an amount of up to 30% by weight, based on the powdered material including any dry additives. 
     
     
         12 . A powdered material for dental applications of  claim 11 , characterised in that the polycarboxylic acid or a copolymer or a salt or an ester thereof, is present in an amount of 1-20%, and preferably 3-15% by weight, based on the powdered material including any dry additives. 
     
     
         13 . A powdered material for orthopaedic applications of  claim 11 , characterised in that the polycarboxylic acid or a copolymer or a salt or an ester thereof is present in an amount of 1-15% and preferably 2-5% by weight, based on the powdered material including any dry additives. 
     
     
         14 . A powdered material of  claim 11 , characterised in that the chemically bonded ceramic material is a material in the group that consists of aluminates, silicates, phosphates, sulphates and combinations thereof, preferably having cations in the group that consists of Ca, Sr and Ba, calcium aluminate cements being most preferred, in which case the first binder phase preferably has a composition between the phases 3CaO•Al 2 O 3  and CaO•2Al 2 O 3 , most preferably about 12CaO•7Al 2 O 3,  optionally as glass phases. 
     
     
         15 . A powdered material according to  claim 11 , characterised in that at least a part or most preferred all the reactive groups of said polycarboxylic acid or salt thereof bond to the chemically bonded ceramic material. 
     
     
         16 . A powdered material according to  claim 11 , characterised in that said polycarboxylic acid or copolymer or salt or an ester thereof is a substance in the group that consists of poly acrylic acid, poly(acrylic-co-maleic acid), poly(itaconic acid), tricarballylic acid; copolymers, salts and esters thereof; and combinations thereof. 
     
     
         17 . A powdered material according to  claim 11 , characterised in that it contains an inert phase additive, preferably including dental glass and preferably at a content of 3-30 weight-% more preferably 5-20%. 
     
     
         18 . A powdered material according to  claim 17 , characterised in that said inert phase additive has a particle size of 0.1-5 μm, more preferably 0.2-2 μm, and most preferably 0.3-0.7 μm. 
     
     
         19 . A powdered material according to  claim 17 , characterised in that said inert phase comprises low amounts of less stable phases or reactive phases including glasses, preferably below 10% of the inert phase content, which less stable phases or reactive phases preferably comprise fluoride and/or phosphorus. 
     
     
         20 . A powdered material according to  claim 11 , characterised in that it has the form of granules, preferably of a size below 1 mm, more preferred below 0.5 mm and most preferred below 0.4 mm and having a granule compaction density above 35%, preferably above 50%, most preferably above 60%. 
     
     
         21 . An aqueous hydration liquid for a powdered material comprising a first binder phase essentially consisting of a cement system, which powdered material has the capacity following saturation with the hydration liquid reacting with said first binder phase to hydrate to a chemically bonded ceramic material, characterised in that said hydration liquid comprises an additive of a second, non-ceramic binder phase, which second binder phase has a different initiation time for setting and/or a different setting rate than the initiation time for hydration and the hydration rate, respectively, of said first binder phase, and in that the hydration liquid together with the powdered material provides for an ion interaction between the hydration reactions and setting reactions of the first binder phase and the second binder phase, respectively. 
     
     
         22 . An aqueous hydration liquid according to  claim 21 , characterised in that said second binder phase comprises a polycarboxylic acid or a copolymer or a salt or an ester thereof. 
     
     
         23 . An aqueous hydration liquid according to  claim 22 , characterised in that at least a part or most preferred all of the reactive groups of said polycarboxylic acid or salt thereof bond to the chemically bonded ceramic material. 
     
     
         24 . An aqueous hydration liquid according to  claim 22 , characterised in that said polycarboxylic acid or copolymer or salt or ester thereof is a substance in the group that consists of poly acrylic acid, poly(acrylic-co-maleic acid), poly(itaconic acid), tricarballylic acid; copolymers, salts and esters thereof; and combinations thereof. 
     
     
         25 . An aqueous hydration liquid according to  claim 22 , characterised in that said polycarboxylic acid or copolymer or salt or ester thereof has a molecular weight of 100-250,000, preferably 1000-100,000. 
     
     
         26 . An aqueous hydration liquid according to  claim 21 , characterised in that it has a pH of 1-7, preferably >3, before the hydration and setting reactions. 
     
     
         27 . A chemically bonded material formed from the system of  claim 1 , the binder phase of which essentially consists of an inorganic cement phase and which material is in situ formed on a substrate or in a cavity, characterised in that said material also comprises a reactive, soluble glass, an in situ formed phase of polyacrylate polymer or co-polymer. 
     
     
         28 . A system according to  claim 5 , characterised in that the system comprises a porous material, preferably a nano/meso-pore structure or a zeolite type structure, that is able to release said acid.